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CVE-2026-50198· NVD / CVE Program· CNA GitHub_M

Wallos: Cross-user subscription cost inference via replacement_subscription_id

Wallos is an open-source, self-hostable personal subscription tracker. Prior to version 4.9.1, an authenticated user can edit their own inactive subscription and set replacement_subscription_id to a subscription ID belonging to another user. The write is accepted, and later the stats logic dereferences that foreign subscription ID without user_id scoping. This lets the attacker infer the victim subscription's monthly-normalized cost by observing changes in their own stats output. This does not expose the full victim subscription object, but it does expose derived financial metadata. This issue has been patched in version 4.9.1.

MediumCVSS 4.3 · v3.1—No exploit Fix available
Published
Aug 31, 2026
Updated
Sep 8, 2026
EPSS
0.3% · 20th percentile
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Action score

17

Monitor

Low priority for now.

CVSS
17 / 40 · 4.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
4.3
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • ellite Wallos

    • < 4.9.1affected

Same product

ellite: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-61640Wallos: SSRF via OIDC Token/UserInfo URL Configuration
    34Monitor
  • CVE-2026-61639Wallos: Zip Slip path traversal in database restore writes files to webroot
    34Monitor
  • CVE-2026-77348Wallos incomplete fix for CVE-2026-33407: unauthenticated httpoxy SSRF still reachable via `endpoints/payments/search.php`
    32Monitor
  • CVE-2026-61641Wallos: OIDC account takeover via email-based account linking without `email_verified` check
    32Monitor
  • CVE-2026-61638Wallos: SSRF via Test Email Notification - unvalidated SMTP host/port
    32Monitor
  • CVE-2026-54600Wallos: Unauthenticated database replacement via import endpoint on fresh install
    32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
ellite Wallos4.9.1 · descriptionVendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
low · data can be read
Integrity
none
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
Low
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-639 · Authorization Bypass Through User-Controlled Key

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

nvd-secondary

Root cause

The endpoint fetches the record by the ID sent in the request, but never checks whether the record belongs to the requesting user.

The bug in code

The whole CWE-639 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
const invoice = await Invoice.findById(req.params.id);res.json(invoice);

Fixed

ts
const invoice = await Invoice.findOne({  id: req.params.id,  ownerId: req.user.id,});if (!invoice) return res.sendStatus(404);res.json(invoice);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records